The detector object allows the user to simulate an integrating detector in an optical system. That is, the detector integrates the optical irradiance over the exposed surface of the detector and saves the integrated result as a single value in units of Amps.
Click Build -> Detectors -> Simple Responsivity in the main model panel.
Click on Arrange Object and drag the detector icon 
to the desired position.
The default detector in Optiscan is square shaped with
dimensions of (1mm x 1mm) and a sampled array size of (500x500).
This detector has a responsivity such that only the upper right hand
corner of the total detector area is sensitive to the light impinging on the detector.
Note that the data values given in the 2-D array represent
the detector responsivity and have units of AMPS/WATT.
The size and sampling of the detector can be reconfigured by the user by
selecting the the PROPERTIES menu item and clicking on GO. This
opens the DETECTOR DIMENSIONS window. This window functions
exactly like the DIMENSIONS windows for the SOURCE object and the
many TARGET objects. The size, offset and sampling rates can be
easily reconfigured by the user. However always remember to
check your sample size so that the total array size of the
detector is reasonable. It is necessary to be careful not to
have a detector whose size is 1cm x 1cm and whose sampling is 1e-7
x 1e-7, because this would result in an array size of 100000x100000,
which is far too large for the computer. A good rule of
thumb is to set your sampling such that the array size of your
detector is between 100 x 100 and 1000 x 1000.
The shape of the detector can be reconfigured by changing
the detector responsivity. Editing the shape of the detector responsivity is
identical to editing the shape of a SOURCE object or the shape of a
TARGET object. The user simply selects one of the
editing options (replace a piece, multiply a piece, or add a piece)
in the menu selection, and follows the instructions to build
the desired detector pattern.
Because Optiscan uses the same subroutine for editing the DETECTOR
responsivity pattern as it uses for editing the SOURCE pattern and the
TARGET patterns, the user needs to be aware that some of the
selections might have different physical meanings or might not be
very useful. For example, adding a phase to the detector is
equivalent to simulating a detector built on a surface that is not flat.
Also, while Optiscan gives the option of choosing a "data mark" as one of
it's catalog patterns, it is highly unlikely that that pattern
will be used for a detector responsivity pattern.
The output data file for the detector can be changed by selecting
the PROPERTIES menu item and clicking on GO. When the new window
appears, click on the RESULTS FILE tab in the upper section of
the window.
Note: if more than one detector is used in a project, they each
must be named differently. This is done in the last step of editing
the detector responsivity. The user must uniquely specify the
filename that the detector pattern is saved under.
Once the desired detector pattern is generated, the user
links the detector into the project workspace.
In this particular workspace, the DELTA object is used to simulate a
scanning system. The light from the source is scanned over the
target and then imaged onto the detector. At each scan position,
the integrated irradiance on the detector is saved to the data
file specified for the detector.
The format of the data file is a simple ascii text file that is tab delimited. The
following table is a sample of how the data looks when imported into a spreadsheet.
| 7.06257092e+002 | 5.92803850e-001 | 4.12283388e+000 | 7.10972730e+002 | 11:51:31 |
| 5.27284897e+002 | 4.54748144e-001 | 3.16376562e+000 | 5.30903411e+002 | 11:51:37 |
| 3.58154522e+002 | 3.21256887e-001 | 2.23453199e+000 | 3.60710311e+002 | 11:51:42 |
| 3.58154522e+002 | 3.21256887e-001 | 2.23453199e+000 | 3.60710311e+002 | 11:51:48 |
| 3.58154522e+002 | 3.21256887e-001 | 2.23453199e+000 | 3.60710311e+002 | 11:51:54 |
| 3.58154522e+002 | 3.21256887e-001 | 2.23453199e+000 | 3.60710311e+002 | 11:52:00 |
| 3.58154522e+002 | 3.21256887e-001 | 2.23453199e+000 | 3.60710311e+002 | 11:52:06 |
| 3.58154522e+002 | 3.21256887e-001 | 2.23453199e+000 | 3.60710311e+002 | 11:52:07 |
| 3.58154522e+002 | 3.21256887e-001 | 2.23453199e+000 | 3.60710311e+002 | 11:52:08 |
| 2.19435807e+002 | 2.06922631e-001 | 1.43902867e+000 | 2.21081758e+002 | 11:52:09 |
| 1.17270009e+002 | 1.16707144e-001 | 8.11256362e-001 | 1.18197973e+002 | 11:52:10 |
| 5.28467181e+001 | 5.49230476e-002 | 3.78620987e-001 | 5.32802621e+001 | 11:52:11 |
| 1.90752679e+001 | 1.90549246e-002 | 0.26448427e-001 | 92207713e+001 | 11:52:13 |
The first three columns represent the current (in AMPS) resulting from the X,Y and Z
polarizations of the incident field, respectively, for each scan position of
the DELTA object. The fourth column is the current resulting from the sum of all three
polarizations, and represents the physical current that would be
measured if the detector is insensitive to polarization. The
three polarization irradiances are given in case the user wishes
to simulate a detector that is sensitive to polarization. The last
column is a time-stamp, which lets the user know at what time the
data was taken.
Note that Optiscan will ONLY APPEND the detector data file, it
will never overwrite it. This means that if the user wishes to
perform a fresh simulation, either the filename of
the previous simulation needs to be changed, or the detector
output filename must be changed.
Please click here to view an example that uses multiple detectors.
Layers may be added to a detector to simulate a detector with
multiple outputs. For instance, the schematic for the
multiple detector example
can be simplified using a single detector icon
that has 4 layers (one for each quadrant). To add layers to a
detector, open the Detector Properties Editor by right clicking
the detector icon and selecting Edit. Select New Layer from the
Menu Items drop-down menu.
Choose the appropriate options to edit the responsivity of the layer.
Each layer should be saved under a different file name, so that
Optiscan can differentiate between the layers when writing the data
output file. Unlike the multiple detector example,
the output data for all 4 layers is written to a single file instead of 4 separate files. The format
of the data file is tab delimited, and looks similar to the following
table when imported into a spreadsheet.
| 0.00E+00 | 0.00E+00 | 0.00E+00 | 0.00E+00 | 1 | 11:23:44 |
| 5.60E-01 | 0.00E+00 | 0.00E+00 | 5.60E-01 | 2 | 11:23:49 |
| 5.60E-01 | 0.00E+00 | 0.00E+00 | 5.60E-01 | 3 | 11:23:54 |
| 5.60E-01 | 0.00E+00 | 0.00E+00 | 5.60E-01 | 4 | 11:23:59 |
| 0.00E+00 | 0.00E+00 | 0.00E+00 | 0.00E+00 | 1 | 11:24:06 |
| 2.49E-01 | 0.00E+00 | 0.00E+00 | 2.49E-01 | 2 | 11:24:11 |
| 2.49E-01 | 0.00E+00 | 0.00E+00 | 2.49E-01 | 3 | 11:24:16 |
| 2.49E-01 | 0.00E+00 | 0.00E+00 | 2.49E-01 | 4 | 11:24:21 |
| 0.00E+00 | 0.00E+00 | 0.00E+00 | 0.00E+00 | 1 | 11:24:27 |
| 5.60E-01 | 0.00E+00 | 0.00E+00 | 5.60E-01 | 2 | 11:24:32 |
| 5.60E-01 | 0.00E+00 | 0.00E+00 | 5.60E-01 | 3 | 11:24:37 |
| 5.60E-01 | 0.00E+00 | 0.00E+00 | 5.60E-01 | 4 | 11:24:42 |
There is a slight bug that occurs when changing the responsivity pattern of the detector. The Y axis is reversed in the viewer that is used to select the window size and position for the new pattern element. This will cause an element positioned in the upper half of the screen in the edit window to actually appear in the lower half of the screen when the responsivity pattern is updated.
